This invention relates to the conversion of chemical energy to electrical energy, and more particularly to a new and improved construction for lithium iodine cells.
One area of use of the present invention is in providing electrical power safely to inaccessible devices in the human environment, for example to an implanted cardiac pacemaker, although the principles of the present invention can be variously applied. The lithium-iodine cell is used with implantable cardiac pacemakers and advantageously has an open circuit voltage about twice that of the mercury cell, does not generate gas during operation, and has a non-corrosive electrolyte.
A cell has been proposed including a lithium anode and a charge transfer complex of an organic donor component and iodine. When more than one cell is needed for certain voltage requirements, providing such a battery for human implantation gives rise to size and capacity considerations. In particular, such a battery must be relatively small in size to be suitable for implantation while at the same time having a relatively larger lithium area to give a longer voltage output. Along with these requirements, each cell should be constructed in a manner preventing an internal electrical short circuit arising from migration or flow of the iodine-containing cathode material. In addition, such a battery desirably will be relatively easy to fabricate.